Re: [PATCH 1/2] difftool: only copy back files modified during directory diff

> Tim Henigan <tim.henigan@gmail.com> writes:
>
>> When 'difftool --dir-diff' is used to compare working tree files,
>> it always copies files from the tmp dir back to the working tree
>> when the diff tool is closed, even if the files were not modified
>> by the diff tool.
>>
>> This causes the file timestamp to change. Files should only be
>> copied from the tmp dir back to the working copy if they were
>> actually modified.
>>
>> Signed-off-by: Tim Henigan <tim.henigan@gmail.com>
>> ---
>>
>> This patch must be applied after commit 304970d on next (diff-no-index:
>> exit(1) if 'diff --quiet <repo file> <external file>' finds changes).
>> because it relies on 'git diff --quiet' to compare files outside the
>> repository.
>>
>>
>>  git-difftool.perl | 7 +++++--
>>  1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/git-difftool.perl b/git-difftool.perl
>> index ae1e052..679a56d 100755
>> --- a/git-difftool.perl
>> +++ b/git-difftool.perl
>> @@ -336,8 +336,11 @@ if (defined($dirdiff)) {
>>       # files were modified during the diff, then the changes
>>       # should be copied back to the working tree
>>       for my $file (@working_tree) {
>> -             copy("$b/$file", "$workdir/$file") or die $!;
>> -             chmod(stat("$b/$file")->mode, "$workdir/$file") or die $!;
>> +             if ((-e "$b/$file") &&
>> +                 (system('git', 'diff', '--quiet', "$b/$file", "$workdir/$file") != 0)) {
>
> Why waste cycles to spawn "git diff" when you only want to find if
> they are byte-for-byte identical *and* when you are importing many
> perl modules from File::* already into the script?
>
>> +                     copy("$b/$file", "$workdir/$file") or die $!;
>> +                     chmod(stat("$b/$file")->mode, "$workdir/$file") or die $!;
>> +             }
>>       }
>>  } else {
>>       if (defined($prompt)) {